'Tantalising prospect'

"The hot summer enabled long-tailed blues and other migratory butterflies to spread northwards into Britain, capitalising on opportunities to breed here while the weather remains warm," he said.

The charity said the large rosy underwing moth had only been recorded on 10 occasions in Britain before this summer and recent sightings raised the "tantalising prospect that the moth is now locally resident".

Experts have not seen such high numbers of this delicately-patterned moth entering the UK for half a century.

Higher than average numbers of the exotic crimson speckled moth have also been recorded along the south coast.